1. Field of the Invention
The present invention relates to an information data recording apparatus for use in a video tape recorder (VTR) having a digital format or the like, for example.
2. Description of the Prior Art
In conventional digital video tape recorders, as U.S. Pat. No. 4,799,113 describes, an input analog video signal is converted into digital data and outer code data for error correction is added to the digital data. Then, the digital data added with the outer code data is shuffled, the shuffled digital data is multiplexed, inner code data for error correction is added to the digital data thus multiplexed and the digital data added with the inner code data is processed in a channel-coding fashion. Further, the digital data that was processed in a channel-coding fashion is amplified and then supplied to a recording rotary head such that the digital data is recorded by the recording rotary head so as to form oblique video tracks.
FIG. 1 of the accompanying drawings shows a digital video tape recorder (DVTR) tape format utilized when digital data is recorded by the digital VTR. As shown in FIG. 1, in the above digital VTR, video data of one field is recorded by six video tracks.
When video data recorded on a magnetic tape is reproduced, the magnetic tape is transported in the direction shown by an open arrow in FIG. 1 and a reproducing head is rotated in the direction shown by a solid arrow in FIG. 1. More specifically, as shown in FIG. 2, a magnetic tape 14 is transported from an entrance tape guide d1 to an exit tape guide d3 and a rotary drum d2 having a reproducing head 15 mounted thereon is rotated as shown by an arrow R1 in FIG. 2. The magnetic head 15 sequentially scans video tracks T1, T2, T3, T4, T5, T6 to reproduce recorded video data. Then, the reproduced data or signal is equalized and amplified. The reproduced signal thus amplified is decoded, de-shuffled and the reproduced signal thus de-shuffled is error-corrected. The reproduced signal thus error-corrected is error-concealed and the reproduced signal thus error-concealed is output as a digital or analog video signal.
In the digital VTR, if data recorded on the narrow tracks on the magnetic tape 14 is reproduced by the reproducing head 15 mounted on the rotary drum d2, when the reproducing head 15 starts to trace the magnetic tape 14, a waveform of a reproduced signal is deteriorated in amplitude by a spacing loss caused by a so-called air film or a so-called impact error of the reproducing head 15 relative to the magnetic tape 14, etc.
FIG. 3 shows an example of such phenomenon that a waveform of a reproduced signal is deteriorated in amplitude. Because the waveform of the reproduced signal is deteriorated in amplitude as shown in FIG. 3, a reproducing error tends to occur and increase at the beginning (portion at which the reproducing head 15 starts to scan) of the video track. There is then the disadvantage that a picture quality of a reproduced picture will be deteriorated.
When the magnetic tape 14 is reproduced by a DT (dynamic tracking head) formed of a bimorph plate bm and the reproducing head 15 mounted on the bimorph plate bm in a so-called dynamic tracking fashion as shown in FIG. 4, the DT head effects the tracking from the beginning of the video track by some suitable methods such as a wobbling or the like. However, until the tracking of the DT head is stabilized from the beginning of the video track, as shown in FIG. 5, a waveform of a reproduced signal is deteriorated in amplitude similarly as described above. As a consequence, a reproducing error tends to occur and increase. There is then the disadvantage that a picture quality of a reproduced picture will be deteriorated.